1. Field of the Invention
The field of the invention generally relates to medical imaging and more particularly relates to methods for determining an insertion trajectory of a tool for reaching a target object, prior to its insertion into a tissular matrix, moving within the tissular matrix, from image acquisition suitable for producing a three-dimensional representation of the tissular matrix.
The field of the invention also relates to the field of robotic systems for positioning a tool for reaching a target object, prior to its insertion into a tissular matrix, within the tissular matrix, from a determination of an insertion trajectory.
2. Description of the Prior Art
Determining an insertion trajectory of a tool for reaching a target object to be inserted into a tissular matrix within the tissular matrix is important in the medical field.
Indeed, chances of success for intervention depend on this determination, since incorrect or insufficiently accurate determination can result in failure in the attempt to reach the target object, or can even cause complications potentially serious for the health of the patient due to damage to some tissue or organs as the tool is moving through the tissular matrix.
Therefore, the medical world is actively researching methods for determining an insertion trajectory.
By way of example, document “Multi-criteria trajectory planning for hepatic radiofrequency ablation” by Baegert et al., in “Medical Image Computing and Computer-Assisted Intervention—MICCAI 2007”, 2007, discloses a method for determining an insertion trajectory for the insertion of a needle for hepatic radiofrequency ablation. This method takes into account a number of parameters, including some strict criteria, such as the needle not passing through a vital organ, bone or a major blood vessel; and other flexible criteria. Associated with each criterion is a function reflecting the state of the criterion as a function of a trajectory taken by the needle. A macro-function is then created by weighted addition of functions. Minimization of the macro-function gives the insertion trajectory.
However, this method does not take into account deformation of the tissular matrix into which the tool is inserted. Yet, deformation of the tissular matrix causes displacement of the target object. Therefore, even though the trajectory has been optimized by this method, it is still possible to miss the target object or touch other tissue.
A method for brachytherapy is known from “Needle Insertion Parameter Optimization for Brachytherapy”, by Dehghan et al., in “IEEE Transactions on Robotics”, Col. 25, No. 2, April 2009. In this method, the aim is to reach a plurality of target objects at the same time. In order to find the insertion trajectory, simulation of the deformation of the prostate, during insertion of the needle along a line passing very close to the target objects, is carried out to detect displacement of the target objects. A new trajectory passing very close to the new positions is determined from the new positions of the target objects. Simulation of the deformation of the prostate, during insertion of the needle along the new trajectory, is carried out, here again, to detect displacement of the target objects.
The steps for determining a new trajectory and of simulation are reiterated until the distance between the needle and the target objects which are displaced is under a threshold, the latter trajectory being the insertion trajectory.
However, this method cannot be applied to determining an insertion trajectory to reach a single target object. In fact, application of the method requires being able to determine the trajectory passing very close to the target objects. Yet, there is no single solution when there is only a single target object. Rather, there are an endless number of solutions.